HUMERAL HEAD REPLACEMENT FOR FOUR-PART FRACTURES AND FRACTURE-DISLOCATIONS

ANDREW GREEN, MD, and TOM R. NORRIS, MD

Prosthetic replacement for acute four-part displaced fractures of the proximal humerus is recommended over other forms of treatment. Fixation of the tuberosities through the rotator cuff attachments avoids potential dehiscence from repairs using the soft osteoporotic tuberosities. Cable supplementation secures tuberosities to the shaft, thereby allowing earlier, safe motion to prevent the stiffness that can accompany these difficult fractures. KEY WORDS: Shoulder joint, four-part fractures, humeral head replacement, internal fixation.

Proximal humerus fractures are the most common hu- meral fractures. In general they are more prevalent dur- ing the latter years of 1ife.l Fortunately, 80% are essen- tially nondisplaced and only require appropriate nonop- erative treatment and rehabilitation to regain shoulder function.’ Treatment of displaced fractures is more complex.

Codman noted that most proximal humerus fractures occurred along the lines of the physeal plates. Subse- quently, Neer recognized the clinical relevance of the four-segment concept and developed the classification system for proximal humerus fractures that remains the standard for evaluating and treating these fractures.4

Four-part fractures and fracture-dislocations account for less than 5% of all proximal humerus fractures.2 The vascular supply to the articular segment is disrupted as a result of the fracture along the anatomic neck.5-7 The vascular supply to the entire arm may be disrupted in three- or four-part proximal humerus fractures’ or with reductions of anterior dislocations. Rupture of the axil- lary artery occurs in 5% of four-part fractures9 It be- hooves the examiner to evaluate the arm meticulously and avoid unnecessary manipulations.

Several forms of treatment, including nonoperative, closed reduction with percutaneous pinning, open reduc- tion, internal fixation with various techniques, and hu- meral head replacement, have been used. The results of closed reduction have been poor.4J9,10 Avascular necro- sis, malunion, and failure of fixation are common com- plications of ORIF. ‘l-l3 More recently, alternative tech- niques, including closed reduction and internal fixation with multiple pins or ORIF with limited soft tissue dis- section and internal fixation, have been advocated for the

From the Department of Orthopaedic Surgery, Brown University, Providence, RI; and the California Pacific Medical Center, San Fran- cisco, CA.

Address reprint requests to Tom R. Norris, MD, California Pacific Medical Center, 2351 Clay St, Suite 510, San Francisco, CA 94115.

Copyright 0 1994 by W. B. Saunders Company 1048-6666/94/0401-0004$05.00/O

valgus impacted fractures involving the articular sur- face.14 Gerber notes that anything less than a perfect anatomic reduction will fail. Long-term follow-up and rigorous outcome evaluation of the latter techniques are still pending.

Acute humeral head replacement has been a predict- able technique for displaced four-part fractures and three- part fractures with osteoporosis or where ORIF is not secure. The general principles of the technique de- scribed by Neer l2 have been up dated with stronger cable fixation to allow earlier motion. Several series have sub- stantiated Neer’s favorable experience.9,11,*5-*7 The out- come is related to patient motivation and the function of the rotator cuff musculotendinous units. Prevention of pain and patient satisfaction are almost uniformly achieved. There has been little evidence to suggest de- terioration of these results with time. In the following sections we will summarize our approach and recent ad- vances in obtaining secure fixation with cable fixation in the treatment of acute four-part fractures and fracture- dislocations using a humeral head replacement.

EVALUATION In most instances, displaced proximal humerus fractures occur as isolated injuries. However, careful attention must be addressed to potential associated injuries or medical conditions, curs in 5% .9

Avulsion of the axillary artery oc- Brachial plexus injuries occur in 5% to 30%.

In Stableforth’s series of four-part fractures with 6.1% brachial plexus injuries, only one-third fully recovered.’ Physical examination directed to assessment of neurovas- cular status of the affected upper extremity may be espe- cially difficult in the acute setting. Nerve conductions with maximal stimulation delineates whether or not the nerves are intact.

The anteroposterior and the axial views of the shoulder trauma series (Fig 1) adequately demonstrate the skeletal injury and usually permit classification of the fracture ac- cording to Neer’s criteria.2 In cases where pain pre- cludes obtaining adequate orthogonal views, or where

Operative Techniques in Orthopaedics, Vol 4, No 1 (January), 1994: pp 13-20 13

Fig. 1. Trauma series radiographs. The scapular plane an- teroposterior of the glenohumeral joint and the axial view will allow recognition of the fracture pattern in the majority of cases. In the cases where axial views are indeterminate, a computed tomographic (CT) scan can define fracture dis- placement most accurately. (Reprinted with permission.24)

there is still a question concerning the fracture pattern, the definition of subtle comminution and degrees of dis- placement is improved by computerized tomography.” A thorough assessment of the patient’s functional needs, capabilities, and motivation is essential. One must rec- ognize the value of prosthetic replacement and avoid de- nying effective surgical treatment to the elderly. Although the glib comment that one can always do a prosthesis later, it is not an innocuous procedure to re- turn to surgery 6 months or later to treat a failed closed reduction. Fixed cuff and tuberosity retraction, dense scar, and further global shortening of all tissues with os- teonecrosis preclude obtaining the result that might be obtained with cuff reconstruction around a prosthesis acutely.‘l Even more difficult later is converting a failed open reduction to a humeral head replacement. Similar problems are noted with late treatment of a closed reduc- tion, except there is usually more scar and a greater chance of nerve injury.‘i

ANESTHESIA AND POSITIONING

We are currently using a long-term interscalene block for all shoulder surgery.(Fig 2A-C)15,‘9*20’21 This avoids complications accompanying high postoperative narcotic requirements following general anesthesia without the interscalene block. We have observed that the analgesic affect of a block using approximately 40 mL of 0.5% Marcaine (bupivacaine; Winthrop-Broen Laboratories, New York, NY) and epinephrine lasts for 12 to 24 hours. Many patients have not required parenteral narcotics af-

14

ter surgery. This obviates annoying respiratory compli- cations and urinary retention associated with high nar- cotic requirements often following general anesthesia.

We routinely use intraoperative autologous blood sal- vage in acute humeral head replacement for fractures in order to avoid using banked blood. It is not uncommon for a patient to lose a unit or more of blood into the region of injury. Even with autologous salvage, older patients occasionally still need a transfusion of bank blood after surgery, ** but the incidence is quite low.

The patient is placed in a modified beach chair posi- tion. A soft bolster is placed under the medial edge of the scapula and the affected shoulder is positioned over the edge of the table so that the arm can be dropped into a vertical position. The adjustable McConnell horseshoe head positioning system (McConnell Orthopaedic Man- ufacturing Company, Greenville, TX)23 is used to protect the head in slight flexion during surgery while increasing superior surgical access (Fig 3). An alcohol and iodine skin preparation is used. The shoulder region is sealed with adherent drapes. The arm is draped free and po- sitioned with the adjustable McConnell arm holder dur- ing surgery, thereby freeing the hands of the assistant for retraction.

SURGICAL TECHNIQUE A longitudinal skin incision is made from the clavicle over the coracoid to the anterior deltoid insertion. Full thick- ness skin and subcutaneous flaps are developed medially and laterally as needed to expose the deltopectoral inter- val. The cephalic vein is preserved with the anterior del- toid muscle. The deltopectoral interval is opened bluntly. The clavipectoral fascia is divided. The upper edge of the insertion of the sternal head of the pectoralis major muscle as well as the anterior insertion of the del- toid muscle may be released to improve exposure. Blunt retractors are placed laterally under the anterior deltoid muscle and medially under the conjoined tendon. Leav- ing the coracoid muscles intact provides additional pro- tection for the brachial plexus. If the head is dislocated anteroinferiorly, it can be removed and saved for poten- tial bone graft (Fig 4A-B). It is important to be aware of the location of peripheral nerves about the shoulder at all times.23 The axillary nerve is palpated along the inferior medial edge of the subscapularis muscle as it passes pos- teriorly contiguous with the inferior capsule. It is visu- alized and protected with a Darrach elevator.

The subacromial space is bluntly freed of adhesions to improve exposure of the rotator cuff tendons. If the an- terior acromion has a significant inferior spur, an anterior acromioplasty can be performed by superiorly retracting the anterior deltoid muscle without releasing its origin. The coracoacromial ligament often is released to enhance superior exposure except in patients with rheumatic ar- thritis, a large preexisting cuff tear, or other complica- tions where weak cuff muscles and proximal humeral mi- gration are anticipated.

The long head of the biceps tendon is the key to defin- ing the injury and exposing the fractures. It is most eas- ily identified as it emerges from under the upper edge of the pectoralis major insertion on the humerus. The bi-

GREEN AND NORRIS

Fig. 2. (A) The cervical anatomy in the right neck is outlined for placement of an interscalene block. The interscalene groove is located behind the sternocleidomastoid (SCM) at the level of the cricoid cartilage (C6). (B) The Stimuplex Sys- tem (Burron Med inc., Bethlehem, PA) uses an insulated long needle with only the tip exposed to conduct electrical cur- rents adjusted between 2 and 4 mA at 2 Hz. (C) When rhyth- mic contractures of the biceps, brachioradialis, or wrist flex- ors are obtained between 5 and 1 ma, 40 mL of long-acting block using 0.5% Marcaine with epinephrlne 1:200,000 are injected in the interscalene groove to provide anesthesia for shoulder surgery.

ceps tendon is followed superiorly to open the rotator The glenohumeral joint is exposed. The humeral interval to the base of the coracoid. Reconstruction of head is retrieved and saved for possible graft. Any re- the fracture fragments facilitates definition of the bicipital maining hematoma and debris are removed from the groove, further definition of the major fracture segments, joint, and the glenoid articular surface is examined. as well as the height the prosthesis will need to rest above the surgical neck on the reconstructed lateral shaft. Any existing fracture in this area between the tuberosities can be opened at the rotator cuff interval between the subscapularis and supraspinatus if it has not already sep- arated. For the most secure tuberosity fixation, heavy nonabsorbable sutures are passed through Sharpie’s fi- bers at the insertion of the rotator cuff tendons (Fig 5A) and then carried around the tuberosities.24 These are initially used as traction sutures and then later used to repair the tuberosities to each other for the horizontal portion of the cuff repair around the prosthesis and through the holes in the fins. The tuberosities them- selves are frequently osteoporotic and hold the suture poorly compared with the site where the cuff inserts. For more secure tuberosity fixation, Dall-Miles cables (Howmedica, Rutherford, NJ) are passed around each tu- berosity and angled distally to the opposite side of the Fig. 3. The patlent rests comfortably in a modified semi-

long head of the biceps for the vertical portion of the fowlers position. The McConnell headrest protects the cer-

repair to the humeral shaft. The cables are stronger than vical spine in slight flexion. At the same time, the area be-

the wire used in years past (Fig 58). Care is taken to tween the neck and the superior shoulder is free for surgical

interdigitate the tuberosity with the upper shift and not approaches and retraction. The arm can be lowered off the

overpull the tuberosities distally with the final tensioning. table for prosthetic replacement in the humeral shaft wlthout detaching the deltoid muscle.

HUMERAL HEAD REPLACEMENT 15

thetic fin just posterior to the bicipital groove. A sponge can be stuffed into the canal to stabilize the position of the trial if necessary. The appropriate height of the humeral component is assessed with several techniques. If the medial calcar is not fractured, then the lowest aspect of the humeral head should be at or slightly above the calcar edge. Tension in the long head of the biceps tendon, rotator cuff, and deltoid muscle with the humerus re- duced is a helpful guide. Most implant systems offer a variety of head sizes to help adjust the soft tissue tension and ensure glenohumeral stability (Fig 6). Scanogram radiographs of the injured and normal extremity obtained preoperatively to assess the length of the humerus allow for measurement above an identifiable landmark on the shaft fracture to assist in determining how high the hu- meral articular surface should rest when compared with the normal length of the opposite humerus.2,24 Lastly, repositioning of the tuberosities above the shaft and be- low the top of the prosthetic articular surface is an excel- lent indication for prosthetic height in this trial run. At the time of the trial reduction, the trial modular heads are placed to assess stability, humeral head translation, cuff tension, and the rotation with a towel clip holding the tuberosity reduction. The humeral head should be able to translate 50% of the humeral head diameter when held in neutral rotation. The prosthesis should be stable anteriorly and posteriorly. At least 140” of elevation and 40” of external rotation should be possible. If this mo- tion is not possible, the two likely problems are the head size is too large or the stem is placed too high in the shaft.

Next the trial component is removed. Two drill holes are made through the humeral cortex several centimeters below the level of the surgical neck fracture on each side of the biceps groove. Heavy nonabsorbable sutures, or in the last 2 years, Dall-Miles cables, are placed through these holes before cementing the humeral stem out to length. The medullary canal is then irrigated and dried. A silastic plug or extra bone fragments are placed distally in the canal. Liquid polymethylmethacrylate cement is injected into the canal. We avoid using excessive ce- ment, pressurizing the cement or extending it above the shaft level. The humeral component is then inserted in

I the desired degree of version and at the predetermined , height. Excess cement is removed at the top of the shaft

to encourage better interdigitation and fracture healing t between the tuberosities. The cement is allowed to cure

before tuberosity repair. Otherwise, pressure on top of the head may cause the prosthesis to settle or change version. Nonabsorbable sutures placed in the rotator cuff insertion and around the tuberosities as traction su-

t tures will be used for the horizontal repair of the tuber- , osities to each other and through holes in the prosthetic

fins (Fig 7A-C). The vertical cables are then tightened to complete the secure tuberosity fixation to the humeral

I shaft, to each other, and to the implant. Tenodesis of the biceps tendon in the repair often is difficult to avoid.

1 Cancellous bone from the articular segment on the un- derside of the tuberosities may need to be contoured to

I improve the fit around the humeral implant and to en- hance healing of the tuberosities to the shaft. Several no. 0 or no. 1 nonabsorbable sutures are also placed in the rotator cuff interval (Fig 8).

GREEN AND NORRIS

Fig. 5. (A) Tag sutures are placed around the greater and lesser tuber- osities and through the rotator cuff. Later, each side is passed through holes in the prosthesis fin for the repair of the tu- beroslties to each other. (6) Cables placed through the cuff attach- ments to the tuberosities and through drill holes in the upper humeral shaft add security to the repair. Passing the cables through holes in this prosthesis fin is omitted to avoid the stress-riser effect that might frag- ment the cables.

Fig. 6. With a modular trial head, the height, ver- s&m, and stability can be assessed by numerous methods including re- duction and temporary tuberosity flxation.

Fig. 7. After securing the tuberosities to each other and at the appropri- ate height below the prosthetic articular sur- face, the cables are tlght- ened and lnterdigltate the tuberosities with the shaft.

Fig. 8. (A) Closure of the rotator interval should still allow suprasplnatus and subscapuiarls gliding with rotation. (B) Operative example of completed repair. The cable boxes are below the humeral head (HH) and should not impinge on the acromlon, coracoid (C), or other soft tissue in this left shoul- der.

After the repair is completed, glenohumeral stability and motion are assessed again. There should be about 50% humeral head translation in an anterior and poste- rior direction and the head should be at the same level as the glenoid. The articular surface rests slightly above the greater tuberosity. The tuberosities interdigitate at the upper end of the shaft without overlapping the shaft and hence avoid overtightening the cuff muscles. This preserves normal humeral height and tension in the del- toid for power. Occasionally, circumferential cables or heavy sutures are placed if the upper shaft is commi- nuted (Fig 9A-B). The limits of glenohumeral motion

Fig. 9. Roentgenographs of two patients with acute pros- thetic reconstruction supplemented with cables. Occasional circumferential cable below the prosthesis collar secures cornminuted fractures of the upper shaft.

and the strength of the tuberosity and soft tissue repair are observed, recorded, and serve as the postoperative guide for the permissible range for safe exercises. With both horizontal and vertical repairs, early motion is an- ticipated.

The deltoid and pectoralis major insertions are repaired if they have been released. A closed suction drainage system is placed deep to the deltoid muscle. The del- topectoral interval is reapproximated and marked with nonabsorbable suture, and the subcutaneous tissue and skin are closed in routine fashion. The arm is placed into a simple shoulder sling.

18 GREEN AND NORRIS

Fig. 10. Clinical follow-up at 6 months demonstrates mild restriction of elevation, normal strength, normal stability, and only minimal discomfort at the extremes of his range of motion following a humeral head replacement for an acute four-part fracture (shown in Figs 4, 6, and 9).

REHABILITATION

The postoperative rehabilitation is individualized in each case. The quality of the bone and soft tissues, the strength of the repair, and patient compliance and moti- vation are considered. Poor quality repairs of the rotator cuff and tuberosities or uncooperative patients are com- mon factors in those who obtain poor results. Direct surgeon supervision is essential in achieving consistent results. The emphasis of rehabilitation progresses from range of motion early on with secure fixation to strength- ening and endurance once shoulder motion has been re- stored and tuberosity healing is likely.

The first stage of rehabilitation consists of passive range of motion exercises. Pendulum range of motion is initiated on the first postoperative day. Additional em-

HUMERAL HEAD REPLACEMENT 19

phasis is placed on the elbow, wrist, and hand motion. Passive forward elevation and external rotation in the su- pine position is only initiated in the immediate postoper- ative period when the repair is thought to be strong and the patient clearly understands the instructions and in- tent of the exercises. Active motion and strengthening are not started in the first 4 weeks in order to protect the tuberosity repair. Tuberosity displacement in the first 3 weeks has been a major cause of complications and poor results in Tanner and Cofield’s series.25

Active motion and isometric deltoid strengthening ex- ercises are initiated after about 6 weeks. Progression to more aggressive passive stretching and strengthening of the rotator cuff muscles is usually delayed until about 3 months after surgery. Stretching is continued daily for at least 1 year following surgery.

The results continue to be better in those patients with acute repairs when compared with late reconstructions (Fig lO).lr

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